The present invention generally relates to electrical power generation systems. More particularly, the present invention relates to a technique for adjusting power output by each of a plurality of electrical generators driven by a single prime mover.
Electrical power generation systems are employed in a number of diverse applications, including aviation, manufacturing, and commercial energy production, to name just a few. As will be appreciated, these systems are generally adapted to convert mechanical power to electrical power that may be used to operate one or more electrical devices or systems requiring such power. Generally, these power generation systems include one or more generators, each generator having a stator and a rotor that rotates with respect to the stator. Such power generation systems also typically include one or more prime movers that supply mechanical power to the rotors. In the case of aviation, for example, prime movers are often gas turbine engines of an aircraft. In some generators, a magnetic field is projected from rotor poles within the rotor and the rotation of the rotor and the magnetic field induces alternating electrical current in the windings of the stator that may be used to power electrical devices. While many generators are produced in which the rotor is configured to rotate within the stator, one skilled in the art will also appreciate that generators may be configured to allow the rotor to rotate about an interior stator.
In the case of a power generation system having multiple generators, it may be desirable to control or balance the electrical power contribution of each generator, including its real and reactive components. Often, when such control is envisaged, a power generation system will include a separate prime mover that provides mechanical power to each generator. The use of independent prime movers for each generator allows the power output to be controlled via adjustment to the applied power of the prime mover and the relative phase angle of the alternating power between the generators. While the coupling of a single generator to a prime mover may be adequate for certain uses, such an arrangement has limitations. For instance, an aircraft includes a finite number of prime movers to drive electrical generators. If the aircraft included two gas turbine engines, only two electrical generators connected to the same grid could be driven by the turbines. If additional generators were needed, it would be possible to couple additional generators to a prime mover. However, as will be appreciated, the coupling of multiple generators to a single prime mover would preclude control of the power output by the generators via adjustments to the common prime mover or the mechanically coupled and non-adjustable phase angles of the generators. Further, the inability to make such adjustments aversely impacts the power rating of a given power generation system.
There exists, therefore, a need for an improved power balancing and adjustment technique that would allow independent adjustment of output power, both real and reactive components, produced by each of a plurality of generators driven by a common prime mover.